A noose was found hanging from a tree outside a museum in Washington DC, authorities say.

The knotted hanging rope was found outside the Hirshhorn Museum - which exhibits contemporary and modern art - on Friday evening.

The museum's officials are investigating how the noose - which is a historically racist symbol used to represent lynching of African Americans - got there, but have reiterated that it doesn't represent the values of the Smithsonian museum.

A noose was found hanging from a tree outside the Hirshhorn museum in Washington DC on Friday authorities say. Pictured is a stock photo and not the noose found

Officials are investigating how this historically racist symbol was placed at the museum (pictured)

'The Smithsonian is committed to be a welcoming, inclusive, and safe place for all,' Smithsonian Secretary David J. Skorton wrote in an email to his staff. 'I know you join me in deploring this act.'

On May 1, authorities found bananas tied in nooses at American University - just a 16-minute drive from the Hirshhorn Museum.

The person in question had written cryptic labels like Harambee - a historically Black American festival- and AKA, which stands for Alpha, Kappa Alpha - Black American sorority.